import java.applet.*;
import java.awt.*;

public class InOrbit extends Applet implements Runnable {

   // Double-buffering stuff.
	private Dimension appletSize;
	private Image offscreenBuffer;
   public Graphics gOff, g;
   
   // Reference of what size it should be
   public static int width = 600;
   public static int height = 600;
   
   // Some variables for the earth
   private int earthDistance = 270;
   private double earthAngVelocity = Math.PI/720;
   private double earthPosition = 0.0;
   
	// Set up space for the person icon
	private Image sun, earth;

	// Set up space for the thread that will run to move the car
	private Thread timeLoop;
   
	public void init() {
	
		// Set up the double buffering.
		g = getGraphics();
		appletSize = getSize();
		offscreenBuffer = createImage(appletSize.width, appletSize.height);
      gOff = offscreenBuffer.getGraphics();
      
      // Get the pictures
      sun = getImage(getDocumentBase(), "img_sun.gif");
      earth = getImage(getDocumentBase(), "img_earth.gif");
      
      // Start up the thread
		timeLoop = new Thread(this);
		timeLoop.start();

   }
   
   public void paint(Graphics g) {
      g.drawImage(offscreenBuffer, 0, 0, null);
   }
   
   public void run() {
   
      // Keep thread looping
      while (true) {
      
         // Clear our display area
         gOff.setColor(Color.white);
         gOff.fillRect(0, 0, InOrbit.width, InOrbit.height+100);
         
         // Draw the pretty sun
         gOff.drawImage(sun, InOrbit.width/2-120, InOrbit.height/2-120, null);
         
         // Calculate the earth's coordinate position
         double earthX = earthDistance * Math.sin(earthPosition);
         double earthY = earthDistance * Math.cos(earthPosition);
         
         // Draw earth (-25 for image offset)
         gOff.drawImage(earth, (int)(InOrbit.width/2+earthX-25), (int)(InOrbit.height/2+earthY-25), null);
         
         // Move the earth
         earthPosition+=earthAngVelocity;
         
         if (earthPosition > 2*Math.PI)
            earthPosition-=2*Math.PI;
         
         // Paint the world
         paint(g);
   
         // Sleep
         try {timeLoop.sleep(10);}
         catch (InterruptedException e) {}
      }
   }
   
   // We don't need the graphics resources anymore.
   public void stop() {
      g.dispose();
      gOff.dispose();
   }
}